SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Additional Information) (Details) $ in Millions	3 Months Ended			12 Months Ended
	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jun. 30, 2019 USD ($) instrument	Jun. 30, 2018 USD ($) instrument	Jun. 30, 2017 instrument	Jul. 01, 2019 USD ($)	Jul. 01, 2018 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Performance period for performance awards				3 years
Minimum percentage for calculating the amortization of actuarial gains and losses under the corridor approach				5.00%
Contract term				one year or less
Allowance for doubtful accounts	$ 4			$ 4	$ 7
Nontrade receivables, current	17			$ 17	$ 10
Number of hedging instruments designated as fair value hedges | instrument				0	0	0
Cumulative effect of accounting changes								$ (3)
Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit)		$ 81	$ 81
Accounting Standards Update 2018-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Tax Cuts And Jobs Act Of 2017 Reclassification From Aoci To Retained Earnings Tax Effect	$ 39
Subsequent Event | Scenario, Forecast [Member] | Accounting Standards Update 2016-02 [Member] | Minimum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Finance and operating lease right-of-use asset							$ 315
Finance and operating lease liability							350
Cumulative effect of accounting changes							20
Subsequent Event | Scenario, Forecast [Member] | Accounting Standards Update 2016-02 [Member] | Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Finance and operating lease right-of-use asset							345
Finance and operating lease liability							380
Cumulative effect of accounting changes							$ 25